Jumper's Knee

Patellar tendinitis, also known as jumper's knee, is a relatively common inflammatory condition that causes pain in the anterior (front) aspect of the knee. The extensor mechanism (Fig.), which includes the quadriceps muscle and patellar tendon, connects the patella (kneecap) to the femur (thighbone) and the tibia (shin). Patellar tendinitis begins as inflammation of the patellar tendon where it attaches to the patella. It can also progress by tearing or degeneration of the tendon.

Jumper's knee is an overuse injury that results from repetitive overloading of the extensor mechanism of the knee. Microtears to the patellar tendon often exceed the body's ability to heal the area unless the aggravating activity is stopped for a period of time. Jumper's knee occurs in many types of athletes but is most common in sports such as basketball, volleyball, or soccer, which require explosive jumping movements. Eccentric loading, which is contraction of the muscle while it is lengthening, occurs when landing from a jump or decelerating. In fact, knee loads up to 7 times body weight occur in a soccer player during kicking and between 9 and 11 times body weight occur in volleyball players during landing. These eccentric loads are thought to be the primary cause of overload in jumper's knee.

Patients with jumper's knee have pain in the area of the patellar tendon, usually near its attachment to the patella. It typically starts as a dull ache but can gradually increase over a period of time. Initially, the soreness is usually felt following a game or workout, but as the condition worsens, one may feel stiffness, grinding, and swelling in the knee. From a diagnostic standpoint, the symptoms can be divided into 4 stages. In stage 1, pain occurs only after activity. The condition does not seem to bother the person before or during the activity. In stage 2, pain is present at the beginning of an activity, seems to dissipate after warming up for a while, and then reappears after the activity. In this stage, the athlete's play is not usually affected. In stage 3, pain occurs during and after activity, affecting performance. In stage 4, the tendon ruptures, causing a chronic weakness of the tendon.

Most patients with jumper's knee, especially those with stage 1 and 2 symptoms, can be treated effectively with nonoperative measures. As with any tendinitis, resting the injured area until the symptoms have subsided is very important. The RICE regimen (rest, ice, compression, elevation) can also help alleviate soreness. Nonsteroidal anti-inflammatory medication, such as aspirin or ibuprofen, and ice massage after activity can help control the swelling and inflammation. Strengthening the quadriceps helps to balance the forces across the patella and take pressure off the patellar tendon. Also, hamstring stretching is extremely important to take pressure off the anterior structures of the knee. Once the inflammation is controlled, the patient with mild to moderate jumper's knee can begin an exercise program focusing on eccentric strengthening exercises. Neoprene sleeves or braces similar to the ones worn by tennis players with tennis elbow can help decrease or disperse the forces on the patella.

The outcome of treatment in patients with jumper's knee is usually very good, especially for those patients in stage 1 and 2, Sometimes in stage 3, the nature of the injury and how it will respond to nonoperative treatment are a little more unpredictable. Even so, few of these patients go on to require surgical intervention. Surgery is reserved for patients who experience debilitating pain for 6 to 12 months despite close adherence to their doctor's instructions. Patients with stage 4 disease who have suffered a complete tendon rupture also need surgery. The overall goal of surgery is to remove the damaged tissue from the tendon and stimulate blood flow to promote healing.

Maximizing quadriceps and hamstring muscle strength and flexibility is the best way to prevent knee injury. Preseason conditioning should concentrate on a gradual increase in repetitive eccentric quadriceps contraction so the tendon can begin to withstand repetitive loading. These measures will help to prevent this inflammatory process. As always, the best treatment is prevention.

Kurt E. Jacobson, M.D.
Columbus, Georgia